Biomedical subjects

Jingli Cai

Publications and source records attributed to Jingli Cai.

7 recordsLinked to original sources

PubMed2003

Nitric oxide acts in a positive feedback loop with BDNF to regulate neural progenitor cell proliferation and differentiation in the mammalian brain.

Nitric oxide (NO) is believed to act as an intercellular signal that regulates synaptic plasticity in mature neurons. We now report that NO also regulates the proliferation and differentiation of mouse brain neural progenitor cells (NPCs). Treatment of dissociated mouse cortical neuroepithelial cluster cell cultures with the NO synthase inhibitor L-NAME or the NO scavenger hemoglobin increased cell proliferation and decreased differentiation of the NPCs into neurons, whereas the NO donor sodium nitroprusside inhibited NPC proliferation and increased neuronal differentiation. Brain-derived neurotrophic factor (BDNF) reduced NPC proliferation and increased the expression of neuronal NO synthase (nNOS) in differentiating neurons. The stimulatory effect of BDNF on neuronal differentation of NPC was blocked by L-NAME and hemoglobin, suggesting that NO produced by the latter cells inhibited proliferation and induced neuronal differentiation of neighboring NPCs. A similar role for NO in regulating the switch of neural stem cells from proliferation to differentiation in the adult brain is suggested by data showing that NO synthase inhibition enhances NPC proliferation and inhibits neuronal differentiation in the subventricular zone of adult mice. These findings identify NO as a paracrine messenger stimulated by neurotrophin signaling in newly generated neurons to control the proliferation and differentiation of NPC, a novel mechanism for the regulation of developmental and adult neurogenesis.

Animals↗

PubMed2003

Designing, testing, and validating a focused stem cell microarray for characterization of neural stem cells and progenitor cells.

Fetal neural stem cells (NSCs) have received great attention not only for their roles in normal development but also for their potential use in the treatment of neurodegenerative disorders. To develop a robust method of assessing the state of stem cells, we have designed, tested, and validated a rodent NSC array. This array consists of 260 genes that include cell type-specific markers for embryonic stem (ES) cells and neural progenitor cells as well as growth factors, cell cycle-related genes, and extracellular matrix molecules known to regulate NSC biology. The 500-bp polymerase chain reaction products amplified and validated by using gene-specific primers were arrayed along with positive controls. Blanks were included for quality control, and some genes were arrayed in duplicate. No cross-hybridization was detected. The quality of the arrays and their sensitivity were also examined by using probes prepared by conventional reverse transcriptase or by using amplified probes prepared by linear polymerase replication (LPR). Both methods showed good reproducibility, and probes prepared by LPR labeling appeared to detect expression of a larger proportion of expressed genes. Expression detected by either method could be verified by RT-PCR with high reproducibility. Using these stem cell chips, we have profiled liver, ES, and neural cells. The cell types could be readily distinguished from each other. Nine markers specific to mouse ES cells and 17 markers found in neural cells were verified as robust markers of the stem cell state. Thus, this focused neural stem array provides a convenient and useful tool for detection and assessment of NSCs and progenitor cells and can reliably distinguish them from other cell populations.

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PubMed2002

Properties of a fetal multipotent neural stem cell (NEP cell).

Multipotent neural stem cells (NSCs) present in the developing neural tube (E10.5, neuroepithelial cells; NEP) were examined for the expression of candidate stem cell markers, and the expression of these markers was compared with later appearing precursor cells (E14.5) that can be distinguished by the expression of embryonic neural cell adhesion molecule (E-NCAM) and A2B5. NEP cells possess gap junctions, express connexins, and appear to lack long cilia. Most candidate markers, including Nestin, Presenilin, Notch, and Numb, were expressed by both NEP cells as well as other cell populations. Fibroblast growth factor receptor 4 (FGFR4), Frizzled 9 (Fz9), and SRY box-containing gene 2 (Sox2) as assessed by immunocytochemistry and in situ hybridization are markers that appear to distinguish NSCs from other precursor cells. Neither Hoechst 33342 nor rhodamine-123 staining, telomerase (Tert) expression, telomerase activity, or breakpoint cluster region protein 1 (Bcrp1) transporter expression could be used to distinguish NEP stem cells from other dividing cells. NEP cells, however, lacked expression of several lineage markers that are expressed by later appearing cells. These included absence of expression of CD44, E-NCAM, A2B5, epidermal growth factor receptor (EGFR), and platelet-derived growth factor receptor-alpha (PDGFR alpha), suggesting that negative selection using cell surface epitopes could be used to isolate stem cell populations from mixed cultures of cells. Using mixed cultures of cells isolated from E14.5 stage embryos, we show that NEP cells can be enriched by depleting differentiating cells that express E-NCAM or A2B5 immunoreactivity. Overall, our results show that a spectrum of markers used in combination can reliably distinguish multipotent NSCs from other precursor cells as well as differentiated cells present in the CNS.

Acetylcholine↗

PubMed2002

Microarray analysis of selected genes in neural stem and progenitor cells.

To access and compare gene expression in fetal neuroepithelial cells (NEPs) and progenitor cells, we have used microarrays containing approximately 500 known genes related to cell cycle regulation, apoptosis, growth and differentiation. We have identified 152 genes that are expressed in NEPs and 209 genes expressed by progenitor cells. The majority of genes (141) detected in NEPs are also present in progenitor populations. There are 68 genes specifically expressed in progenitors with little or no expression in NEPs, and a few genes that appear to be present exclusively in NEPs. Using cell sorting, RT-PCR, in situ hybridization or immunocytochemistry, we have examined the segregation of expression to neuronal and glial progenitors, and identified several that appeared to be enriched in neuronal (e.g. CDK5, neuropilin, EphrinB2, FGF11) or glial (e.g. CXCR4, RhoC, CD44, tenascin C) precursors. Our data provide a first report of gene expression profiles of neural stem and progenitor cells at early stages of development, and provide evidence for the potential roles of specific cell cycle regulators, chemokines, cytokines and extracellular matrix molecules in neural development and lineage segregation.

Animals↗

PubMed2002

Stem cell and precursor cell therapy.

Strategies for cell replacement therapy have been guided by the success in the hematopoietic stem cell field. In this review, we discuss the basis of this success and examine whether this stem cell transplant model can be replicated in other systems where stem cell therapy is being evaluated. We conclude that identifying the most primitive stem cell and using it for transplant therapy may not be appropriate in all systems. We suggest alternative strategies such as progenitor cell replacement, inductive factors, bioengineering organs, in utero transplants, or any approach that takes advantage of the unique properties of the tissue and the stem cell type which, are more likely to provide effective functional replacement.

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PubMedDate not supplied

Identifying and tracking neural stem cells.

Hematopoietic stem cells, unlike neural stem cells, can be readily identified and isolated from developing and adult cell populations using positive and negative selection criteria. Isolating stem cells and progenitor cells from neural tissue has been more difficult because of difficulties in separating cells in solid tissue, the limited numbers of stem cells that persist in the adult, and the paucity of rigorously characterized markers. Nevertheless, strategies that have worked successfully in hematopoietic stem cell isolation can be adapted to isolate multiple classes of stem and progenitor cells from neural tissue. Neural stem cells also share cellular and molecular properties with other stem cell populations that may serve as surrogate identifiers of multipotentiality. Such potential markers are described. Unlike hematopoietic stem cells, tracking neural cells after transplantation is both necessary and more difficult. It will therefore be necessary to develop invasive and non-invasive strategies to follow transplanted cells and develop useful quantifiable readouts. Some potential strategies are described and current results are discussed.

Cell Separation↗

PubMedDate not supplied

Distinguishing features of progenitor cells in the late embryonic and adult hippocampus.

Adult neurogenesis occurs within the subgranular layer of the hippocampal dentate gyrus. In this study, we examined dividing cells in the late embryonic and adult rat hippocampus to identify distinguishing characteristics and potential neural stem cell population(s), as identified by the putative neural stem cell markers FGFR4 and Sox1. In embryonic hippocampal cells in primary culture, basic fibroblast factor caused cell proliferation, increased telomerase activity and upregulation of FGFR4 mRNA. In both the embryonic and adult brains, proliferating cells express Sox1, as well as markers for neuronal- and glial-restricted precursors. However, the cell markers associated with cells expressing proliferative cell nuclear antigen (PCNA) and Sox1 differed between late embryonic and adult hippocampus, suggesting that there are important differences between adult and embryonic neurogenesis.

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